The invention set forth in this specification pertains to the delivery of a gas to the pulmonary tract of a living body. This invention is considered to be of particular significance in connection with the delivery of oxygen to a human being as, for example, during oxygen therapy.
In the past it has been quite common to deliver oxygen to a person needing such therapy by enclosing the area around the nose and the mouth of the individual with a so-called "tent" and supplying oxygen to the interior of the tent so that the person will tend to inhale an oxygen enriched gas from the interior of the tent. It is also common to administer oxygen by either conveying pure oxygen or an oxygen enriched air mixture directly to the nostrils of such a person through small tubes commonly referred to as nasal cannula. At times the structure consisting of two of such tubes joined together in one manner or another is referred to as a nasal cannula structure.
It has been determined that these widely used procedures for delivering oxygen to the pulmonary tract of an individual needing oxygen therapy are comparatively wasteful of oxygen. As a consequence of this a number of efforts have been made to develop oxygen delivery structures which operate in such a manner as to use less oxygen than required by prior therapy methods in order to maintain a specific desired oxygen level within the blood of an individual. A number of different devices have been developed for this purpose. In general it may be considered that all of such prior devices for this purpose have employed one or more internal structures to regulate or tend to regulate the flow of oxygen to the patient in accordance with the patient's breathing cycle. These prior gas delivery procedures which are related to the breathing cycle have been directed towards modulating the flow of oxygen or oxygen enriched gas so that such gas does not escape or does not significantly escape to the ambient air before it is inhaled.
It will be recognized that such apparatuses which are designed to regulate the flow of such gas such as oxygen can be quite beneficial and desirable. However, it is considered that these prior devices are wasteful of oxygen inasmuch as they relate to the delivery of oxygen to the pulmonary tract of the body to successive breathing cycles. While under some conditions this may be quite desirable there are conditions where this is somewhat undesirable because it results in the extravagant utilization of oxygen without the achievement of a maximum of benefit in maintaining the oxygen level of the blood.